1. Field of the Invention
The present invention relates to a method to refurbish a diesel injector valve seat wherein the valve seat is of greater diameter than the valve guide bore.
2. Description of the Related Art
Straub, et al., U.S. Pat. No. 6,339,877, is already known to Detroit Diesel Corporation. Basically, the patent discloses an apparatus and method of refurbishing a valve seat disposed at a predetermined angle relative to the centerline of an associated valve bore in a workpiece wherein the apparatus includes a support structure on which the workpiece is located such that the centerline of the valve bore is assigned with a known reference axis. The apparatus further includes a tool having a lapping portion corresponding to the valve seat and a drive mechanism for moving the tool along the known reference axis such that the lapping portion is brought into engagement with the valve seat and for rotating the tool relative to the workpiece to lap the valve seat. The method generally includes locating the workpiece in a predetermined position such that the centerline of the valve bore is aligned with the known reference axis and moving the tool having a lapping portion corresponding to the valve seat along the known reference axis such that the lapping portion is brought into engagement with the valve seat. The tool is rotated relative to the workpiece to the lap the valve seat, and the tool is then moved along the known reference axis to disengage the lapping portion from the valve seat.
Earnhardt, U.S. Pat. No. 6,035,532 discloses a method of manufacturing a conical valve seat wherein the valve seat surface is placed in alignment with a cutting edge of a pattern impression pin, a predetermined amount of pressure is applied to the valve seat to move the valve seat surface relative to the cutting edge of a pattern impression pin to form a groove in the seat, hardening the seat member and then grinding a conical surface in the seat surface to finish it.
Dantes, U.S. Patent Publication No, 2005/0028365 discloses a method for manufacturing a valve-seat member of a fuel injector having helical grooves in a recess to generate a swirl, a valve-seat surface of the valve-seat member cooperating with a valve-closure member of a fuel injector to form a sealing seat, and the recess being used to guide the valve-closure member. The method includes producing a blank of the valve-seat member, introducing the recess, and at least one spray-discharge orifice into the blank of the valve-seat member and introducing helical grooves into the recess. The introduction of helical grooves into the recess is carried out by a non-cutting machining step.